An ion implanter includes an ion source for converting a gas or a solid material into a well-defined ion beam. The ion beam typically is mass analyzed to eliminate undesired ion species, accelerated to a desired energy, and implanted into a target. The ion beam may be distributed over the target area by electrostatic or magnetic beam scanning, by target movement, or by a combination of beam scanning and target movement. The ion beam may be a spot beam or a ribbon beam having a long dimension and a short dimension.
Implantation of an ion species may allow a workpiece to be split. The species forms microbubbles in the workpiece material. These microbubbles are pockets of a gas or regions of an implanted species below the surface of the workpiece that may be arranged to form a weakened or porous layer in the workpiece. A later process, such as a thermal, chemical, or mechanical process, is used to split the workpiece into two layers along the weakened layer or porous layer.
FIG. 1 is an embodiment of an implanted workpiece with a layer of microbubbles. A species 300, which may be, for example, hydrogen, is implanted into the workpiece 206. In some embodiments, hydrogen may be implanted at approximately 6E16 cm−2 to produce a layer of microbubbles 301 below the surface of the workpiece 206. The workpiece 206 is later split along this layer of microbubbles 301. In other embodiments, helium, oxygen, nitrogen, other rare or noble gases, or a combination of gases are used to form the layer of microbubbles 301. This may be performed in one implant or a series of implants. Greater implant energy of the species 300 generally will result in a greater implant depth of microbubbles 301. Greater implant dose of the species 300 generally will result in a greater concentration of the species 300 that form the microbubbles 301.
Previous methods have implanted hydrogen or a combination of hydrogen and helium to split a workpiece. However, a uniform dose of hydrogen or hydrogen and helium causes random split initiation. Using a thermal splitting process with a uniform dose means that there is no control over where the split begins. This may cause damage to the workpiece depending on its orientation in a thermal processing unit. A uniform dose also may make mechanical splitting methods more difficult or time-consuming. Furthermore, the implanted dose may not be optimized to enable propagation of the split. Accordingly, there is a need in the art for an improved process to implant a workpiece before splitting.